Lithium ion battery packs are known in the art and find frequent use in such items as so-called smart phones, pad/tablet-based computers, laptop computers, and so forth. Users appreciate short charging time and rapid charging typically requires higher current flow (at present, sometimes as high as 10 A). Such battery packs often contain a standalone battery protector integrated circuit with power field effect transistors (FETs) to control bi-directional current flow.
Battery voltage must be sensed to ensure accurate charging but safety issues can arise in these regards. The voltage drop across the aforementioned FETs is relatively large with high charging currents. Providing a voltage sensing path around the power FETs poses risk in that such a path can provide a sneak current path for overcharging or over discharging the battery under various fault conditions.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various examples of the present teachings. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various examples of the present teachings. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.